An unlikely hero in a scary situation.

The local news says Paul DeLeon is considered a "quasi security guard" for businesses around a Fresno, California liquor store.

And this week, the homeless 53-year-old man proved he's earned the title.

The "Good Samaritan" was outside the liquor store when witnesses say a man allegedly began kicking and punching his girlfriend until she was unconscious. When he saw the 19-year-old being pummeled, DeLeon sprung into action.

"I mean he was kicking her hard too, right in the head, and I couldn't just stand there and do nothing," DeLeon told ABC News affiliate KGO. "I grabbed my mace, and I maced him. He drove off and said something, 'I'm gonna come back for you...' He did."

And when he returned, the man was armed with a pistol. By the time he arrived, an ambulance had come and taken the woman to the hospital. But that didn't stop him from opening fire on DeLeon, and striking him once in the arm.

"The bullet went through," DeLeon told KGO. "It's not bad."

What the alleged assaulter didn't know was that DeLeon is a registered gun owner, and he was armed for the confrontation.

Despite his injury, DeLeon managed to grab his registered handgun and returned fire at the suspect. After exchanging a few rounds, DeLeon fended him off and the man fled in a white Lexus. Police got reports of the Lexus speeding down highway 41 in Fresno, hitting 100 mph. Later, police found the car unattended at an intersection in downtown Fresno.

It is unknown whether the suspect suffered any injuries in the fire fight, but he could be facing spousal abuse charges and assault with a firearm.

"He probably would have killed her," DeLeon said. "I mean I have no doubt in my mind he wouldn't have stopped. She was out of it and he was still kicking her."